The present invention relates to a gas turbine engine, and more particularly to a rotor blade attachment thereof.
Gas turbine engines often include a multiple of rotor assemblies within a fan, compressor and turbine section. Each rotor assembly has a multitude of blades attached about a circumference of a rotor disk. Each of the blades is spaced a distance apart from adjacent blades to accommodate movement and expansion during operation. Each blade includes a root section that attaches to the rotor disk, a platform section, and an airfoil section that extends radially outwardly from the platform section.
Gas turbine engine rotor blades are typically attached in a rotor disk rim through a fir-tree-type root attachment section. The blades are then locked into place with bolts, peening, locking wires, pins, keys, plates, or other locks. The blades need not fit too tightly in the rotor disk due to the centrifugal forces during engine operation. Some blade movement reduces the vibrational stresses produced by high-velocity airstreams between the blades.
Referring to FIG. 1A, current rotor blade fir-tree-type root design attachments are symmetrical in shape and may vary from one lobe to four or more lobe tooth attachment designs. Although effective, this symmetry results in a reduced cross-sectional area between each blade which may limit Low Cycle Fatigue (LCF) and shear strength (P/A) (FIG. 1B) capability.